Convert lower camelCase to PascalCase in c#?

Question

I need to convert camelcase keys to Pascal key and I got good solution from stackoverflow. But the issue is I don't know how to exclude . in conversion.

Please find the below example:

var input= "customer.presentAddress.streetName";

Expected Output is

var output= "Customer.PresentAddress.StreetName";

PlayGround : Please click here

Answer 1

As per the @Hans Passant and @JamesS comments, I have rewritten the code :

public static string ToPascalCase(this string input)
        {
          return string.Join('.',input.Split('.').Select(x => ConvertToPascalCase(x)));
        }
        private static string ConvertToPascalCase(string input)
        {
            Regex invalidCharsRgx = new Regex(@"[^_a-zA-Z0-9]");
            Regex whiteSpace = new Regex(@"(?<=\s)");
            Regex startsWithLowerCaseChar = new Regex("^[a-z]");
            Regex firstCharFollowedByUpperCasesOnly = new Regex("(?<=[A-Z])[A-Z0-9]+$");
            Regex lowerCaseNextToNumber = new Regex("(?<=[0-9])[a-z]");
            Regex upperCaseInside = new Regex("(?<=[A-Z])[A-Z]+?((?=[A-Z][a-z])|(?=[0-9]))");

            // replace white spaces with undescore, then replace all invalid chars with empty string
            var pascalCase = invalidCharsRgx.Replace(whiteSpace.Replace(input, "_"), string.Empty)
                // split by underscores
                .Split(new char[] { '_' }, StringSplitOptions.RemoveEmptyEntries)
                // set first letter to uppercase
                .Select(w => startsWithLowerCaseChar.Replace(w, m => m.Value.ToUpper()))
                // replace second and all following upper case letters to lower if there is no next lower (ABC -> Abc)
                .Select(w => firstCharFollowedByUpperCasesOnly.Replace(w, m => m.Value.ToLower()))
                // set upper case the first lower case following a number (Ab9cd -> Ab9Cd)
                .Select(w => lowerCaseNextToNumber.Replace(w, m => m.Value.ToUpper()))
                // lower second and next upper case letters except the last if it follows by any lower (ABcDEf -> AbcDef)
                .Select(w => upperCaseInside.Replace(w, m => m.Value.ToLower()));

            return string.Concat(pascalCase);
        }